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    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID 2269c
                                                       Report Date: 09-May-96:17:01
                                                       Version: **********
                                                       Check-in Date: **********

1.Proposal Title:
GALAXY POPULATIONS IN INTERMEDIATE REDSHIFT CLUSTERS
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2. Scientific Category   3. Proposal For  4. Proposal Type        5. Continuation ID
GALAXIES & CLUSTERS         GO                                       <none>
Sub Category

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6. Principal Investigator   Institution                    Country    Telephone
Dr. Warrick J Couch         UNIVERSITY OF NEW SOUTH WALE   AUSTRALIA  61-2-697-4578
PROF
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7. Abstract
We request WF/PC time to image at high resolution the members of the rich southern
cluster AC 114 at z=0.31 which we have studied extensively at the AAT using both
fiber-optic spectroscopy and multi-colour photometry. Our comprehensive ground-based
data has allowed us to measure precise line indices and colours for individual
galaxies in this cluster and, along with data on other distant clusters, to
construct a unifying picture for the various phenomena associated with the Butcher-
Oemler effect whereby different galaxies are seen at different stages of star-
formation activity within a simple cycle. The WF/PC data will allow us to
morphologically classify galaxies at various stages in this cycle and resolve many
of the questions left unanswered by the ground based data. The AAT catalogue is the
largest, most complete spectroscopic and photometric data set where, by virtue of
the moderate redshift, detailed information is available for all galaxies to a fixed
magnitude limit. As such, our sample forms the ideal first target for HST studies of
the evolution of galaxies in dense environments.
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8. Scientific Key Words:   DISTANT GALAXY CLUSTERS, GALAXY EVOLUTION, GALAXY
MORPHOLOGY
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9. Est obs time (hours) pri: 10.00    par: 0       10. Num targs pri: 3      par: 0
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11. Instruments requested:  WF/PC
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I. GENERAL FORM    Proposal 2269c
PI: Dr. Warrick J Couch
Proposal Title:
GALAXY POPULATIONS IN INTERMEDIATE REDSHIFT CLUSTERS
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1. Proposers:
Proposers                        Institution                       Country       ESA
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Prof. Richard S Ellis            DURHAM UNIVERSITY                 UK             X
Dr. Ray M Sharples               DURHAM UNIVERSITY                 UK             X
P.I. Warrick J Couch             UNIVERSITY OF NEW SOUTH WALES     AUSTRALIA      X
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  3. Description of proposed observations.
  We propose broad-band two-colour imaging of AC 114 with WF/PC using the F555W
 and F814W bands. The images will be exposed to depths required to provide
 morphological classifications of the bursting and post-starburst galaxies
 identified in our R < 20 spectroscopic and photometric ground-based samples.
 Morphological classification will proceed via quantitative surface photometry of
 the images obtained in each colour (coadding where necessary to improve S/N) with
 the derivation of surface brightness profiles and disk/bulge ratios. The images
 in each band will also be combined to map each galaxy in colour and thus
 determine the location and extent of the blue star star-forming regions. Non-
 linear MEM techniques will be employed to further enhance these processes. The
 F555W and F814W filters represent the best compromise between a number of
 factors: (1) maximising throughput (2) providing an adequate colour wavelength
 baseline (3) ensuring adequate calibration during the first period of HST
 science.
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  4. Justification of need for HST observations.
  The largest 4-5m ground-based telescopes have been pushed to their observational
 limits in terms of detection, photometry and spectroscopy in investigations of
 the Butcher-Oemler effect. While there is now a much clearer understanding of the
 effect, the inability to spatially resolve the distant cluster galaxies from the
 ground remains the major barrier to resolving the key issues. None of the
 scientific objectives can be met from the ground because of atmospheric seeing
 limitations. Despite some progress with image enhancement techniques, such
 systems are not suitable for faint objects and do not reach the 0.1-0.2 arcsec
 resolution required for precise morphological work.
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  5. Description of special scheduling requirements.
  Our main requirement is to obtain complete morphological information for the
 R<20 members in AC 114 identified and studied spectroscopically at the AAT. The
 R<20 limit corresponds to V < 21.0 and  I < 19.3. Using z=0.3 model galaxies with
 r**1/4 and exponential disk profiles sampled with the present degraded PSF, we
 determine that a minimum of 8. 10**5 electrons above background are required for
 morphological studies. From the most recent WF/PC performance data we estimate
 that total on-source exposures of 6.0 hours in F555W and 5.8 hours in F814W on
 our AC 114 field are required for us to pursue our morphological study of the
 galaxies in this cluster. In order to correct for cosmic ray events, frame pairs
 are required, but to avoid charge defect problems associated with low background
 levels, ideally no individual sub-exposure should be less than 1 orbit.
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  7. Data reduction and analysis plans.
  The WF/PC frames will be reduced on STARLINK using software proven for the
 analysis of extended galaxies (Couch and Newell 1984). All applicants have
 extensive experience in multicolour cluster photometry (Couch et al 1983) and in
 surface photometry of bright spheroidal and multi-component galaxies (Sharples,
 thesis).
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 10. Resources to be supplied by investigator's institution(s).
  Durham University has excellent computing facilities consisting of a 5 microVAX
 cluster and 3 image processing workstations. There is one STARLINK programmer
 dedicated to 2-D image processing requirements.
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11. Address Information
Name:  WARRICK J COUCH                                     Category: PI
Institution: UNIVERSITY OF NEW SOUTH WALES
Address:  SCHOOL OF PHYSICS
          PO BOX 1
          KENSINGTON
City: SYDNEY                                    State: NS
Zip Code: 2033                                  Country: AUSTRALIA
Telephone: 61-2-697-4578
Telex (or e-mail): AA26054
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TARGET LIST    a) Fixed Targets                                                                    ID = 2269c            [  4]
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 1 |     2      |           3           |              4             |  5     |   6    |  7  |              8
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Tar|   Target   |         Target        |            Target          |Coord   | Radial |Acqui|FLX|     Flux data
No |    Name    |       Description     |           Position         |Eqnx    |  Vel.  |Prblm|REF|
   |            |                       |                            |        |        |     |   |
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1   AC114        CLUSTER OF GALAXIES;    RA=22H 56M 00.64S +/- 0.2S,  B1950    Z=0.31         1   V = 21.0 +/- 0.2
                 DISTANT GALAXY          DEC=-35D 04' 18.6" +/- 4.5"                          2   I = 20.1 +/- 0.2
                 CLUSTER
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EXPOSURE LOGSHEET                                                                                  ID = 2269c            [  5]
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 1      |   2   |      3    |  4   |   5   |   6   |    7   |   8   |       9       |10 |   11  |   12    |13 |14|        15
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  Line  |  Seq  |   Target  |Instr | Oper. | Aper  |Spectral|Central|   Optional    |Num|  Time |   S/N   |Flx|Pr|     Special
 Number | Name  |    Name   |Config| Mode  |or FOV |Element |Waveln.|  Parameters   |Exp|       |Rel. Time|Ref|  |   Requirements
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1                AC114       WFC    IMAGE   ALL     F555W            CR-SPLIT=NO     1   1500S   760       1   1  SEQ 1-2 NO GAP
                                                                                                 21740S           CYCLE 1 / 1-2
     Comments: MINIMUM USEFUL SUB-EXPOSURE IS
               2500S OR 1 ORBIT
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1.5              AC114       WFC    IMAGE   ALL     F555W            CR-SPLIT=NO     9   2300S   760       1   1
                                                                                                 21740S
     Comments: MINIMUM USEFUL SUB-EXPOSURE IS
               2500S OR 1 ORBIT
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2                AC114       WFC    IMAGE   ALL     F814W            CR-SPLIT=NO     9   2300S   644       2   2
                                                                                                 20980S
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            Summary Form for Proposal 2269c                                                                              [  6]

  Item                          Used in this proposal
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  Configurations                WFC
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  Opmodes                       IMAGE
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  Optional Parameters           CR-SPLIT=NO
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  Proposal for                  GO
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  S/C Hours                     10.00
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  Scientific Category           GALAXIES & CLUSTERS
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  Scientific Sub-category      <none>
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  Special Requirements          SEQ 1-2 NO GAP; CYCLE 1 / 1-2
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  Spectral Elements             F555W F814W
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  Target Names                  AC114
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